An Investigation into Transport Protocols and Data Transport ...

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10.3. Future Directions 254 mial increase of cwnd facilitates fast utilisation of network resources, whilst the adaptive backoff and resetting of β to half upon consecutive drops in throughput due to competing traffic greatly aids fast convergence and fairness. However, the polynomial increases also results in a large overhead - especially at long latencies (unsurprising as the polynomial increase is time based). As such, some tuning of this parameter and matching to real networks will be beneficial. The delayed-based FAST algorithm also demonstrates similar attributes to H-TCP. However, the major disadvantage of such delayed-based algorithms is the requirement of network buffering to be proportional to the number of FAST flows sharing the bottleneck link. As demonstrated throughput Chapter 8, when the network buffers are small, FAST has some very undesirable throughput, fairness and friendliness performances. Therefore, further research into the choice of γ is required. Also a mechanism whereby FAST does not cause these large fluctuations in goodput when there is insufficient buffering should be developed. Several other TCP congestion control algorithms have been proposed but were chosen to either not be within the scope of the research or were not incorporated due to time constraints. • TCP Limited Slow-Start [Flo04] is an adaptation of the slow start algorithm to prevent large numbers of retransmits due to the exponential growth of cwnd by switching to an aggressive linear increase of cwnd when cwnd is larger than a threshold value. • TCP Westwood [CGM + 02, GM, WVS + 02] utilises RTT to determine the appropriate bandwidth delay product in order to determine the appropriate cwnd size for the TCP flow. Unlike FAST, it still incor-
10.3. Future Directions 255 porates standard additive increase of 1 packet, and will back-off cwnd upon loss to the determined bandwidth delay product value. It also utilises a filter on the RTT to enable the detection of losses due to BER rather than real network congestion. • TCP AFRICA [KRB05] was devised to incorporate the benefits of HSTCP with that of delayed based congestion control such that the flow is more stable and fair against competing flows. • XCP [KHR] is an extension of the ECN methodology whereby the state of network congestion is determined not by end-hosts but from information gathered directly through intermittent routers. The basic idea is that each XCP enabled router determines the appropriate window sizes that each host-pair should use based on internal calculations. This enables the adaptation of sending rates to optimal fair-share allocations in the order of one RTT. Whilst offering potentially the most efficient form of global congestion control, it also requires much infrastructure in the form of XCP capable routers, and XCP capable hosts in order to fully appreciate its benefits. 10.3.2 AQM/RED Whilst the deployment of AQM solutions is currently limited, it is suggested that AQM should [BCC98, FJ93] be implemented to aid fair sharing of network resources. This dissertation only focused upon the use of drop tail queuing disciplines to study the effects of New-TCP algorithms, and only touched upon a WRED solution to optimise SACK processing. There is therefore a large area of
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An Investigation into Transport Pro
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Contents List of Figures . . . . .
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Contents 5 4.6 Summary . . . . . .
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Contents 7 8.2 Test Calibration . .
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Contents 9 10.3.5 Further Tests . .
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List of Figures 11 5.7 Effect on cw
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List of Figures 13 8.16 Unfairness
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List of Figures 15 8.32 Friendlines
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List of Figures 17 9.19 Dynamic swi
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List of Figures 19 D.1 Internet pat
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List of Tables 21 A.1 Hardware and
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Publications And Workshops Some of
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1.2. Research Scope 25 • Identifi
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1.4. Dissertation Outline 27 • Id
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Chapter 2 High Energy Particle Phys
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2.2. Analysis Methods 31 the data i
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2.3. Data Volumes and Regional Cent
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2.3. Data Volumes and Regional Cent
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2.4. Data Transfer Requirements 37
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2.5. Summary 39 data, the most impo
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3.1. Data Intercommunication 41 mov
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3.2. Network Monitoring 43 Whilst l
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3.2. Network Monitoring 45 Internet
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3.2. Network Monitoring 47 1 0.8 Bo
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Chapter 4 Transmission Control Prot
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4.1. Overview 51 Throughput Delay L
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4.2. Protocol Description 53 is dep
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4.2. Protocol Description 55 As a r
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4.3. Congestion Control 57 excessiv
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4.3. Congestion Control 59 probe fo
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4.4. Retransmission Timeout 61 tion
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4.5. TCP Variants 63 mechanisms are
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4.5. TCP Variants 65 connection ini
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4.5. TCP Variants 67 20 15 cwnd sst
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4.5. TCP Variants 69 no more acks t
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4.5. TCP Variants 71 [Hoe96]. In bo
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4.5. TCP Variants 73 TCP Timestamps
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4.6. Summary 75 traffic for a parti
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Chapter 5 TCP For High Performance
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5.1. TCP Hardware Requirements 79 G
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5.1. TCP Hardware Requirements 81 1
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5.1. TCP Hardware Requirements 83 C
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5.2. TCP Tuning & Performance Impro
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5.3. Network Aid in Congestion Dete
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5.3. Network Aid in Congestion Dete
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5.4. Analysis of AIMD Congestion Co
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5.5. Summary 109 5.5 Summary Even t
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6.1. Survey of New-TCP Algorithms 1
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6.2. Discussion and Deployment Cons
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6.3. Summary 133 6.3 Summary The re
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Chapter 7 Testing Framework for the
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7.1. Metrics 137 various New-TCP al
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7.1. Metrics 139 assuming equilibri
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7.2. Environment 141 of packets in
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7.2. Environment 143 T 0 B, T T 1 F
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Chapter 8 Systematic Tests of New-T
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8.1. Methodology 147 fed into the d
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8.1. Methodology 149 Various other
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8.2. Test Calibration 151 Goodput (
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8.2. Test Calibration 153 cwnd and
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8.2. Test Calibration 155 100 1 Agg
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8.2. Test Calibration 157 1000 FAST
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8.3. Results 159 10 100 Total Throu
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8.3. Results 161 14 12 HSTCP 1 α H
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8.3. Results 163 cwnd (packets) 120
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8.3. Results 165 Fraction Bytes Ret
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8.3. Results 167 1200 1000 HTCP 1 H
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8.3. Results 169 This is due to the
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8.3. Results 171 4000 3500 3000 HTC
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8.3. Results 173 800 700 600 Standa
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8.3. Results 175 1 1 Fairness Ratio
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8.3. Results 177 10 100 Total Throu
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8.3. Results 179 1000 Standard TCP
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8.3. Results 181 600 500 Standard T
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8.4. Discussion of Results 183 Asym
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8.4. Discussion of Results 185 New-
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8.4. Discussion of Results 187 Asym
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8.5. Summary 189 The importance of
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9.1. Transfer Tests Across Dedicate
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Page 203 and 204: 9.1. Transfer Tests Across Dedicate
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Page 243 and 244: 9.4. Summary 243 performance of sin
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Page 247 and 248: 10.1. Summary 247 PCs. But at 1Gb/s
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Page 253: 10.3. Future Directions 253 low ove
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Page 287 and 288: A.2. Network Interface Cards 287 ha
Page 289 and 290: B.2. Wide Area Network Tests 289 Da
Page 291 and 292: C.3. DataTAG 291 Cisco 7606 Cisco 7
Page 293 and 294: Appendix D Network Paths of Interne
Page 295 and 296: 295 ham02gva.datatag.org:192.91.239
Page 297 and 298: Bibliography 297 [All03] [AMA + 99]
Page 299 and 300: Bibliography 299 [BPSK96] H. Balakr
Page 301 and 302: Bibliography 301 [DC02] [ea02] [FF9
Page 303 and 304: Bibliography 303 [Flo03] [Flo04] S.
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Bibliography 305 [Hoe96] [IET] [Jac
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Bibliography 307 [KRB05] [Lah00] [L
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Bibliography 309 [MHR03] [MM96] M.
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Bibliography 311 [Pos81a] J. Postel
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Bibliography 313 [tePM] IEPM Intern
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